Dynamic daylight simulations: Impact of weather file’s choice

• Results obtained with IWEC, Meteonorm and Satel-Light are comparable.
• The calculated direct sunlight’s incidence is similar for all weather files.
• Annual and Monthly Light Exposures show significant differences (20%).
• Differences in dynamic daylight metrics values are not significant.

This paper is the second step of a research project aimed at investigating the impact of the use of different weather data files on daylight simulations’ results. Simulations were carried out for a simple standalone office using three weather files (IWEC, Meteonorm and Satel-Light) for two European locations (Copenhagen and Rome); moreover the office’s exposure was changed according to the four main orientations (North, East, South and West).Results were analyzed both in terms of Annual and Monthly Light Exposures, dynamic daylight performance metrics (DA, DAcon, UDI) and sunlight’s incidence.It was demonstrated that differences between the results obtained with the different weather files are more significant considering Annual and Monthly Light Exposures (highest value 20%), whereas they decrease when analyzing illuminances with a statistical approach (DA, DAcon, UDI). The analysis of sunlight’s incidence also determined similar results using the three weather data files and the maximum difference is 5% independently from the orientation.